1. Field of the Invention
The present invention relates generally to navigation and communication devices for vehicles, and more particularly to vehicle avoidance of regions having signal interference from high energy (HE) electromagnetic (EM) radiation emitters.
2. Description of the Related Art
Radio based navigation and communications devices such as automatic direction finders (ADF), very high frequency (VHF) and high frequency (HF) radios and Global Navigation Satellite System (GNSS) devices are vulnerable to signal interference from high energy (HE) electromagnetic (EM) radiation emitters. Vehicles entering regions of interference by these HE EM radiation emitters may experience impaired ability to navigate and communicate using radio-based navigation and communications devices.
Government agencies are typically responsible for making sure that EM radiation emitters do not interfere with navigation and communication receivers which are compliant with their individual interference specifications, when those receivers are used with specified stations at specified frequencies and within specified volumes and routes.
To achieve additional performance, economy, or to avoid various threats, it is desired that vehicles be able to depart from routings where interference-controlled paths have been previously determined. Presently, vehicles are neither able to determine such routings on their own using prescribed frequencies and stations, nor can they determine interference-controlled routings to the desired destination using alternative frequencies and stations.